Motion Planning for a Six-Legged Lunar Robot

This paper studies the motion of a large and highly mobile six-legged lunar vehicle called ATHLETE, developed by the Jet Propulsion Laboratory. This vehicle rolls on wheels when possible, but can use the wheels as feet to walk when necessary. While gaited walking may suffice for most situations, rough and steep terrain requires novel sequences of footsteps and postural adjustments that are specifically adapted to local geometric and physical properties. This paper presents a planner to compute these motions that combines graph searching techniques to generate a sequence of candidate footfalls with probabilistic sample-based planning to generate continuous motions to reach them. The viability of this approach is demonstrated in simulation on several example terrains, even one that requires rappelling.